No Post beep (even in Barebones config), fans running, but No Boot. After 3 days boots & runs normally until I shut it down

BiG BaD mOfO

Reputable
Feb 1, 2016
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4,510
Hi all,
Hey, i have a similar problem where i get no video, no POST beep and fans keep running. Also the power and reset button do not work when this happens. I have to shut it off by unplugging the main AC power cable. It wont start after repeated attempts like this. Then after 3 to 4 days of inactivity it starts up and works totally normally. But once I shut it down I have to avoid touching it for 3 days to start it back up.
My computer also seems to be loosing time every time I startup. Replaced the battery but no good. The old battery was fine when I tested it on a multi meter.
Took all apart for Barebones testing except CPU because I did not have Thermal paste to reapply. Did try with only CPU, MOBO and CPU fan to start but got no beep. Then put all back together and Left it on for four hours still no beep or boot, just fans and mobo voltage phase LED's were on. Then started it after 3 days and it came on. No major software or hardware changes done.
Btw POST beep speaker is fine.
When it is running and I want to know how to diagnose which component is faulty so I can change it?

I also got a message about a month ago saying" Reboot and select proper boot device or insert boot device in selected boot device and press a key" Then the computer started after i removed and reconnected the HDD.

No OC done ever.
Specs - 5 Years old Except cooler, graphics card and RAM which are 3 yrs old approx
Windows 7 Ultimate 64 Bit
AMD Phenom 2 X4 955 Black edition
MSI 890GXM G65
WD Caviar Blue 500 Gb 5400rpm
Galaxy Nvidia Gtx 650 1GB DDR5 (Has no Extra power connectors other than the PCI slot)
Corsair Vengeance 1600 2x 4Gb ( Running at 1333mhz)
Corsair H80i Hydro dual fan liquid cooler
Corsair CX 600 PSU
Samsung DVD RW
Case CM Elite 430
 
I've had an eerily similar situation as this and while I understand my build is totally different than this the PSU made me wonder. I am using this: Ultra X4 750-Watt Modular Power Supply V2. Is this an OK PSU or should I think about changing?

My issue seems to happen only when using the X.M.P. turned on in the bios (does this use more power than standard, it does right but 0.15 V increase per dimm doesn't seem like much to me). When X.M.P. is turned off my build seems to work great. I believe it is certified 80plus bronze.

Is there a way to "test"the PSU either in the bios or while running Windows to see if it is giving the proper amount of power, or at least the proper power for what I need for my rig?